This invention relates to a steering mechanism for use with medical catheters or other devices which need to be positioned in difficult locations.
In many medical procedures, it is necessary to position a catheter at a location within a patient's body. A typical emplacement for the distal end of a catheter might be within a ventricle of the heart, by way of the femoral vein. In so passing a catheter through the femoral vein, it is necessary to avoid obstructions, vessel junctions and the like, and to make sharp turns to position the distal end of the catheter within the ventricle. Other medical procedures involve similar difficulties in placing a catheter.
In conventional catheters used today, the tip of the catheter may be bent, or may include a stylet which is bent, such that a semipermanent curve is given to the distal end of the catheter so that a physician may guide the distal end thereof towards the treatment location. A disadvantage with this type of apparatus is that the curvature of the bend is not adjustable while the catheter is in the body, and any change in the curvature requires the physician to remove the catheter and reshape the distal end.
There is a need for a steering mechanism for catheters and other devices wherein the distal end of the device can be manipulated at will from a location outside the patient's body or outside the apparatus in which the device is placed. Accordingly, it is an object of the present invention to provide such a steering mechanism, and in particular to provide such a mechanism which provides a wide range of steerability.
It is another object of the invention to provide such a mechanism which may be completely manipulated with one hand.
It is a further object of the invention to provide such a steering mechanism wherein the distal end of the mechanism may be bent into varying shapes for placement in different positions while the mechanism is in use.
Other objects and advantages will more fully appear in the course-of the following discussion.
cl SUMMARY OF THE INVENTION
The steering mechanism of the invention includes a flexible steering shaft attached to a controller. The controller includes a handle with a central bore in which one or more steering wires are carried. The steering shaft includes a flexible coil, at the distal end of which a ferrule is positioned. Mounted on the ferrule is a lead spring, which extends to the distal tip of the steering shaft. The steering wire has a distal end which is welded or otherwise affixed to the distal end of the lead spring. Tension may be placed on the steering wire by manipulating the controller, thus turning the distal end of the steering shaft.
In use, the steering shaft is inserted into a lumen of a catheter, and the controller is manipulated to turn the distal end of the catheter.
In a preferred embodiment, two steering wires are provided, one attached to each side of the lead spring at the distal end of the steering shaft. The two steering wires may be attached at points directly opposite one another on the lead spring, or they may be offset to provide for different configurations of the distal end of the steering shaft when tension is placed on one, the other, or both steering wires.
In one embodiment, the controller includes a wedge mounted transversely to the handle of the controller, the wedge receiving the steering wire and being tapered such that pushing the wedge in one direction places tension on the steering wire, and pushing it in the other direction releases tension from the steering wire. In a two steering wire embodiment, two wedges are provided, positioned such that their tapered portions run opposite to one another, for providing two-way steering of the distal end of the steering shaft.
In another embodiment of the invention, two steering wires may be attached to a rotatable shaft which is mounted on an axis transverse to a longitudinal axis of the handle of the controller. A central knob is attached to the shaft, such that turning it one way places tension on one of the steering wires and turning it the other way places tension on the other steering wire.
In an alternative embodiment of the invention, the two steering wires are attached to two separate rotatable shafts mounted on the controller, and the shafts may be independently rotated for independent control of the steering wires.
In a preferred embodiment of the invention, regions of the steering shaft at the distal end thereof are enlarged in diameter to allow for greater bending of the distal end at those regions.
Variations on these and other embodiments are described below.